1. Field of the Invention
This invention is a medical device having a frontal attachment comprising a retractable needle. One aspect of the invention relates to a frontal attachment that desirably clips onto and in sliding engagement with a connector housing comprising a unitarily molded or otherwise formed needle retraction cavity and at least a body or barrel portion of an associated medical device in laterally spaced-apart relation to each other. The associated medical device can include, for example, a syringe, IV-catheter insertion device, infusion set, fluid collection device, or other medical apparatus with which a retractable needle can be used. One preferred embodiment of the invention relates to a medical device comprising a retractable needle that is selectively attachable to a conventional needless syringe or other cooperatively attachable vascular fluid collection apparatus, the device being specially adapted for use in sampling blood gas, and more particularly, for sampling arterial blood gas.
Another aspect of the invention relates to a frontal attachment having a rearwardly biased retractable needle and a needle retraction mechanism, wherein the needle is aligned longitudinally with a fluid flow path through the connector housing to the associated apparatus whenever fluid is flowing through the needle but is not aligned with a needle retraction chamber until needle retraction is initiated.
Another aspect of the invention relates to a connector housing desirably comprising a needle retraction chamber open at one end and having a needle retraction cavity with a longitudinal axis that is substantially parallel to but laterally offset from the longitudinal axis or centerline of the needle during use and prior to needle retraction.
Another aspect of the invention relates to a connector housing that is desirably engaged with and slidable in relation to a frontal attachment in a direction substantially transverse to the longitudinal axis through a retractable needle seated in the frontal attachment. The slidable movement is desirably initiated by applying opposed forces to at least the frontal attachment and the connector housing. One of the oppositely directed forces can be a resistance force.
Another aspect of the invention relates to a medical device inside which a retractable needle holder and needle seated in a frontal attachment prior to use are biased into a safe position following use so that the needle tip is not exposed and the frontal attachment device cannot be reused. When the needle and needle holder are in the “safe position,” the needle holder and a portion of the needle are desirably disposed in a retraction cavity inside a needle retraction chamber that is not coaxially aligned with the needle when fluid is passing through the needle during use of the medical device.
2. Description of Related Art
Conventional syringes comprising a generally cylindrical barrel, a needle projecting forwardly from the barrel, and a plunger slidably disposed inside the barrel through an opening in the rear of the barrel are well known. Some conventional syringes are made with a luer slip or luer lock connector on the front of the barrel to which a cooperatively configured changeable needle or needle hub is attachable to allow needles of different gauges or sizes to be used. The luer tips of such syringes are typically exposed to bacterial or viral contamination by incidental contact with a person or object during use. A notable exception is U.S. Pat. No. 8,343,094, which discloses a syringe that can be used with a changeable needle and also has a protective guard structure that extends forwardly past the luer tip to reduce the likelihood of contamination by contact.
More recently, syringes and other medical devices having fixed or changeable needles have been designed to embody various “safety” elements in an effort to control the spread of blood-borne pathogens and contamination by contact with exposed needles, bodily fluids or other contaminated objects or surfaces. Such devices sometimes include retractable needles, as in U.S. Pat. No. 7,351,224, but the term “safety” is also frequently applied to products having moveable guards, shields or covers that must be manipulated manually to cover or block access to the tip of a needle that is not retractable following use. Use of such moveable guards, shields or covers is not effective unless the needle is first removed from the patient or another device in relation to which fluid has been injected or extracted. The use of products having moveable guards, shields or covers as “safety” elements has in some cases been reported to increase the number of accidental needle-sticks, and such devices should be distinguished from those having retractable needles, and especially from those having needles that can be retracted while still inserted into a patient or other device. Examples of devices incorporating a “safety” element that is not a retractable needle are disclosed in U.S. Pat. No. 5,370,628 and U.S. Pat. No. 8,500,690. U.S. Pat. No. 8,500,690 acknowledges that the safety shield disclosed there cannot fully encompass the needle cannula until it is fully removed from the patient and also acknowledges that automatic shielding may be triggered by the intentional or unintentional release of the finger tabs by the user at any time following removal of the packaging cover.
In the previously known medical devices having retractable needles and needle retraction mechanisms, a needle retraction cavity is typically provided that is aligned with the longitudinal axis through the needle during use. In such devices a barrel and/or a cylindrical interior portion of a plunger handle often serve as the needle retraction cavity. An example of such a device is disclosed in U.S. Pat. No. 7,351,224.
In other medical devices, the needle retraction cavity is made as a unitary part of a body comprising both a barrel and a needle retraction cavity, each having a longitudinal axis that is substantially parallel to and spaced apart from the longitudinal axis of the other during use. In those devices, however, the needle and needle retraction cavity remain aligned during both use and needle retraction, and a cross-over fluid pathway is provided between the barrel and the rear end of the needle. An example of such a device in which the needle is not rearwardly biased is disclosed in U.S. Pat. No. 4,941,883. An example of such a device in which the needle is rearwardly biased is disclosed in U.S. Pat. No. 6,468,250.
Among the medical devices having retractable needles, some have an actuator to which a retraction force is manually applied to retract the needle by sliding it rearwardly into a needle retraction cavity following use. Other devices either automatically retract the needle into a needle retraction cavity following use or require a separate and subsequently applied manual force to initiate needle retraction. The manual force needed to initiate needle retraction is sometimes applied longitudinally, such as through all or a portion of a plunger to reposition a plug or retainer member or to cut, fracture or pierce an interfering element. Such devices are disclosed, for example, in U.S. Pat. No. 5,503,010 and in U.S. Pub. No. 2008/0287881. Sometimes the initiating manual force is applied by pivoting a trigger element into an angular relationship with the longitudinal axis of the needle to reposition an element interfering with the retraction of a rearwardly biased element as shown, for example, in U.S. Pub. No. 2010/0317999. Sometimes the initiating force is applied by lateral movement of an actuator disposed inside a housing that comprises a needle retraction mechanism as disclosed, for example, in U.S. Pub. No. 2009/0306601. Sometimes the initiating force is applied by depressing a lever bar in a direction transverse to the longitudinal axis through the needle to pull a trigger pin and thereby release a slidable piston assembly biased rearwardly by a spring as disclosed, for example, in U.S. Pat. No. 4,973,316. A few known medical devices, as disclosed for example in U.S. Pat. No. 7,351,224, have needle retraction mechanisms with rearwardly biased needles that enable the needle to be retracted directly from the patient, but many others do not.
Another known medical device, disclosed in European Application No. EP 0 479 303 A1, is a frontal attachment for a luer tip syringe in which the frontal attachment comprises a needle retraction cavity having a longitudinal axis that is parallel to and spaced apart from the longitudinal axis of a connector portion to which a luer tip of the syringe is connected. With that device, however, the needle is coaxially aligned with the retraction cavity at all times and a fluid pathway is provided for fluid cross-over between the syringe and the needle. Also, even though the syringe with which the syringe can be used is characterized as “conventional” in the disclosure, the plunger portion of the syringe is specially adapted by the addition of a pushrod extending forwardly from the plunger seal that cooperates with the frontal attachment. Needle retraction in the device is initiated manually with an assist provided by a tensioned rubber band connected to the distal end of the retraction cavity.
Although the safety benefits of medical devices having retractable needles have become more widely recognized and appreciated in recent years, in the interest of safety for patients, their families and health care workers, a need remains for medical devices having an economical and reliable frontal attachment for use with medical apparatus such as a conventional syringe or IV-catheter introducer having a luer lock or luer slip connector. The needed devices should be usable without requiring special adaptation or modification of an associated medical apparatus (such as a syringe), have few parts, be comparatively inexpensive to manufacture, and embody a selectively attachable, retractable needle of a desired size and a needle retraction mechanism that can be activated with one hand and will retract the needle directly from a patient without applying a force during needle retraction.